MoS₂-Based NH₃ Sensor for In Situ Helicobacter pylori Detection

Detection of Helicobacter pylori is essential for the prevention of gastric cancer. By detecting the metabolized NH 3, it was able to noninvasively reveal the state of H. pylori; however, it is still a challenge since the metabolized NH 3 concentration is much lower for conventional gas sensors. Herein, we developed a MoS 2 -based NH 3 sensor for continuous, real-time monitoring of H. pylori growth. The atomic thin layer and the all-exposed surface of MoS 2 facilitate NH 3 adsorption and charge transferring. A high-response NH 3 sensor was prepared by surface decoration of MoS 2 by depositing metal nanoparticles. The Fe-decorated MoS 2 sensor outperformed with a high response of 40.9% for 5.7 ppm of NH 3 at 25 ± 2 °C, low LOD (6.2 ppb), and long-term stability with a response of 12.5% for 5.7 ppm of NH 3 after 5 months. The Fe-decorated MoS 2 sensor was applied to the detection of H. pylori and the real-time in situ monitoring of its 92 h growth cycle. The NH 3 release curve of the exponential phase during H. pylori growth was continuously monitored, and the NH 3 concentration was quantified. The maximum specific rate of NH 3 release was 0.195 ± 0.005 h –1, which is well-consistent with the nature of H. pylori growth. This study opens up a technological roadmap for noninvasive detection of H. pylori in the future.